It’s no secret that most cats love fish. Which is strange, when you consider that fish isn’t what they would normally eat in the wild. But there’s a good reason why your cat gets excited when you open a can of tuna or sear some salmon.
Cats Favor Umami Flavors
All mammals have five basic tastes: sweet, salty, sour, bitter, and umami. But that doesn’t mean all mammals’ taste receptors function equally. Human receptors, for example, are more sensitive to sweet tastes. Cats are obligate carnivores with a nutritional need for a primarily meat diet. So it makes sense that their receptors are more sensitive to the savory notes of umami. And for cats, fish packs a big umami punch.
But just because fish appeals so strongly to cats, it doesn’t mean that they should eat it all the time. Just like humans shouldn’t constantly snack on cookies and cake (although many of them wish they could!). Here’s why you should limit your cat’s fish intake.
Fish Is Not a Complete Protein for Cats
When cats consume too much fish in their diet, they risk deficiencies in Vitamin B1, and Thiamine, which can have extremely negative effects on their wellbeing. The calcium to phosphorous levels are also too low. These deficiencies can cause problems like neurological and kidney issues.
Urinary Tract Issues and Hyperthyroidism
Overconsumption of fish can cause urinary tract issues, since most are high in magnesium. Fish is also high in iodine, something which cats don’t need much of. It’s a possible cause of hyperthyroidism in cats, along with the Polybrominated Diphenyl Ethers sometimes found in canned cat food.
High Mercury Levels in Fish, and Other Toxins
Predatory fish — the kind most often found in cat food — tend to have high levels of mercury. Even humans are cautioned to limit how often they have tuna. The same would go for cats, and tuna is the most common predatory fish used in our food. But mercury is not just found in tuna. Salmon and trout have it too. Predatory fish, in addition, have higher levels of other toxins and pesticides from being higher on the food chain and eating smaller fish.
Cats Get Addicted to Fish
It’s important for cats to have a varied diet, containing several different protein sources. It’s actually instinctual for cats to latch onto certain foods and consider them safe over others. They learn it from their mothers. Fish, especially tuna, is very triggering when it comes to feline food addiction. It’s up to humans to offer a variety of foods so cats don’t get stuck on just one flavor.
Fish Is an Allergen
The top three allergens for cats are fish, beef, and dairy.
So…No Fish for Cats?
Does this mean your cat should forego fish entirely? Not necessarily. What’s important is making sure your cat gets a variety of proteins for their meals, and to rotate what you give them regularly. Your cat should enjoy their food, just like you do. And that means that, barring any medical conditions, their diet doesn’t have to be absolutely perfect. A small amount of fish won’t be harmful for most cats. The key being a small amount.
Hidden Fish in Cat Food
If you want to feed your cat less fish, you need to start checking the ingredient labels of cat food. You’d be surprised at how often fish is included, even when the main protein is chicken, duck or another meat. Fish is an easy flavor enhancer, and way too many companies use it. Try to buy cat food that contains as few ingredients as possible. If you can avoid those that list undefined ingredients like “natural flavorings,” even better.
If you are going to feed a fish cat food to your cat, here’s the best way to do it. Make fish an occasional meal, part of a balanced diet, and check that fish isn’t contained in the other foods you are feeding.
What About Omega-3 Fatty Acids?
Yes, cats need Omega-3 fatty acids for their health. Getting it from fish oil supplements is acceptable, if it’s not already in their food. But while it’s contained in vegetable sources also, such as flax and chia seeds, cats can’t metabolize them. The one plant-based oil that works for cats is oil from sea algae.
Can I Ever Give Fish as a Treat?
It’s okay to offer fish as an occasional treat, if there are no medical reasons to avoid it. But don’t give it very often! Sardines in water make good treats under these conditions (they have lots of those Omega-3s). So do single-ingredient cat treats, like freeze dried salmon or minnows. As much as cats love tuna, it should be last on your list of fish to give as treats. It just has too many heavy metals. A tiny bit goes a long way! Remember that your cat is only one-tenth your size (or smaller), and figure out portions according to that criteria.
You may be wondering how much fish I get in my diet. The answer is almost none! My human is big on reading cat food ingredient labels, and I almost never get cat treats that are primarily fish. When I do, it’s usually because we were given a sample. Very occasionally, my human will give me a taste of salmon if she is having it for lunch or dinner, or a taste of sardines, but she never gives me tuna. I’m pretty healthy for a 9-1/2 year old cat, so she must be doing something right!
I hope you found this helpful! Do you limit your cat’s fish intake or not? Let’s discuss it in the comments.
Here is more from me about cat nutrition and cat health: